Test preflight probing sends and skips if necessary

diff --git a/lightning/src/ln/payment_tests.rs b/lightning/src/ln/payment_tests.rs
index 835ad67f1bc458638bf1061cfd56890070a916fa..3def4e3629bf2fb98d227d9a95e5b1faf6493bc9 100644 (file)
--- a/lightning/src/ln/payment_tests.rs
+++ b/lightning/src/ln/payment_tests.rs
@@ -25,6 +25,7 @@ use crate::ln::outbound_payment::{IDEMPOTENCY_TIMEOUT_TICKS, Retry};
 use crate::routing::gossip::{EffectiveCapacity, RoutingFees};
 use crate::routing::router::{get_route, Path, PaymentParameters, Route, Router, RouteHint, RouteHintHop, RouteHop, RouteParameters, find_route};
 use crate::routing::scoring::ChannelUsage;
+use crate::util::config::UserConfig;
 use crate::util::test_utils;
 use crate::util::errors::APIError;
 use crate::util::ser::Writeable;
@@ -1304,6 +1305,102 @@ fn onchain_failed_probe_yields_event() {
        assert!(!nodes[0].node.has_pending_payments());
 }
 
+#[test]
+fn preflight_probes_yield_event_and_skip() {
+       let chanmon_cfgs = create_chanmon_cfgs(5);
+       let node_cfgs = create_node_cfgs(5, &chanmon_cfgs);
+
+       // We alleviate the HTLC max-in-flight limit, as otherwise we'd always be limited through that.
+       let mut no_htlc_limit_config = test_default_channel_config();
+       no_htlc_limit_config.channel_handshake_config.max_inbound_htlc_value_in_flight_percent_of_channel = 100;
+
+       let user_configs = std::iter::repeat(no_htlc_limit_config).take(5).map(|c| Some(c)).collect::<Vec<Option<UserConfig>>>();
+       let node_chanmgrs = create_node_chanmgrs(5, &node_cfgs, &user_configs);
+       let nodes = create_network(5, &node_cfgs, &node_chanmgrs);
+
+       // Setup channel topology:
+       //                    (30k:0)- N2 -(1M:0)
+       //                   /                  \
+       //  N0 -(100k:0)-> N1                    N4
+       //                   \                  /
+       //                    (70k:0)- N3 -(1M:0)
+       //
+       let first_chan_update = create_announced_chan_between_nodes_with_value(&nodes, 0, 1, 100_000, 0).0;
+       create_announced_chan_between_nodes_with_value(&nodes, 1, 2, 30_000, 0);
+       create_announced_chan_between_nodes_with_value(&nodes, 1, 3, 70_000, 0);
+       create_announced_chan_between_nodes_with_value(&nodes, 2, 4, 1_000_000, 0);
+       create_announced_chan_between_nodes_with_value(&nodes, 3, 4, 1_000_000, 0);
+
+       let mut invoice_features = Bolt11InvoiceFeatures::empty();
+       invoice_features.set_basic_mpp_optional();
+
+       let mut payment_params = PaymentParameters::from_node_id(nodes[4].node.get_our_node_id(), TEST_FINAL_CLTV)
+               .with_bolt11_features(invoice_features).unwrap();
+
+       let route_params = RouteParameters { payment_params, final_value_msat: 80_000_000 };
+       let res = nodes[0].node.send_preflight_probes(route_params, None).unwrap();
+
+       // We check that only one probe was sent, the other one was skipped due to limited liquidity.
+       assert_eq!(res.len(), 1);
+       let log_msg = format!("Skipped sending payment probe to avoid putting channel {} under the liquidity limit.",
+               first_chan_update.contents.short_channel_id);
+       node_cfgs[0].logger.assert_log_contains("lightning::ln::channelmanager", &log_msg, 1);
+
+       let (payment_hash, payment_id) = res.first().unwrap();
+
+       // node[0] -- update_add_htlcs -> node[1]
+       check_added_monitors!(nodes[0], 1);
+       let probe_event = SendEvent::from_node(&nodes[0]);
+       nodes[1].node.handle_update_add_htlc(&nodes[0].node.get_our_node_id(), &probe_event.msgs[0]);
+       check_added_monitors!(nodes[1], 0);
+       commitment_signed_dance!(nodes[1], nodes[0], probe_event.commitment_msg, false);
+       expect_pending_htlcs_forwardable!(nodes[1]);
+
+       // node[1] -- update_add_htlcs -> node[2]
+       check_added_monitors!(nodes[1], 1);
+       let probe_event = SendEvent::from_node(&nodes[1]);
+       nodes[2].node.handle_update_add_htlc(&nodes[1].node.get_our_node_id(), &probe_event.msgs[0]);
+       check_added_monitors!(nodes[2], 0);
+       commitment_signed_dance!(nodes[2], nodes[1], probe_event.commitment_msg, false);
+       expect_pending_htlcs_forwardable!(nodes[2]);
+
+       // node[2] -- update_add_htlcs -> node[4]
+       check_added_monitors!(nodes[2], 1);
+       let probe_event = SendEvent::from_node(&nodes[2]);
+       nodes[4].node.handle_update_add_htlc(&nodes[2].node.get_our_node_id(), &probe_event.msgs[0]);
+       check_added_monitors!(nodes[4], 0);
+       commitment_signed_dance!(nodes[4], nodes[2], probe_event.commitment_msg, true, true);
+
+       // node[2] <- update_fail_htlcs -- node[4]
+       let updates = get_htlc_update_msgs!(nodes[4], nodes[2].node.get_our_node_id());
+       nodes[2].node.handle_update_fail_htlc(&nodes[4].node.get_our_node_id(), &updates.update_fail_htlcs[0]);
+       check_added_monitors!(nodes[2], 0);
+       commitment_signed_dance!(nodes[2], nodes[4], updates.commitment_signed, true);
+
+       // node[1] <- update_fail_htlcs -- node[2]
+       let updates = get_htlc_update_msgs!(nodes[2], nodes[1].node.get_our_node_id());
+       nodes[1].node.handle_update_fail_htlc(&nodes[2].node.get_our_node_id(), &updates.update_fail_htlcs[0]);
+       check_added_monitors!(nodes[1], 0);
+       commitment_signed_dance!(nodes[1], nodes[2], updates.commitment_signed, true);
+
+       // node[0] <- update_fail_htlcs -- node[1]
+       let updates = get_htlc_update_msgs!(nodes[1], nodes[0].node.get_our_node_id());
+       nodes[0].node.handle_update_fail_htlc(&nodes[1].node.get_our_node_id(), &updates.update_fail_htlcs[0]);
+       check_added_monitors!(nodes[0], 0);
+       commitment_signed_dance!(nodes[0], nodes[1], updates.commitment_signed, false);
+
+       let mut events = nodes[0].node.get_and_clear_pending_events();
+       assert_eq!(events.len(), 1);
+       match events.drain(..).next().unwrap() {
+               crate::events::Event::ProbeSuccessful { payment_id: ev_pid, payment_hash: ev_ph, .. } => {
+                       assert_eq!(*payment_id, ev_pid);
+                       assert_eq!(*payment_hash, ev_ph);
+               },
+               _ => panic!(),
+       };
+       assert!(!nodes[0].node.has_pending_payments());
+}
+
 #[test]
 fn claimed_send_payment_idempotent() {
        // Tests that `send_payment` (and friends) are (reasonably) idempotent.